Apparatus for polishing toroidal surfaces

ABSTRACT

Apparatus for polishing toroidal surfaces on ophthalmic lenses. In accordance with a preferred embodiment, a toroidal polishing tool is driven in a non-rotating orbital manner while being supported by a gimbal having pivot axes which are vertically displaced from one another so that the lapping surface of the tool will, in its movement, define and always move on a toroidal surface fixed in space. By properly spacing the gimbal axes relative to the vertex of the tool surface, the fixed toroidal surface in space will have the same radial dimensions as the tool surface and the lens surface to be polished. Therefore, by positioning the lens so that its surface will be on the fixed toroidal surface in space, the lens will be effectively polished by the moving tool and can be held stationary throughout the polishing operation. Because the lens can be held stationary, greater machine speeds and polishing rates can be achieved. An improved breakup motion is also provided in the system to prevent the formation of ridges or grooves on the lens surface.

United States Patent 1 APPARATUS FOR POLISHING TOROIDAL SURFACES [75]Inventor: Wiktor J. Rupp, Lowell, Mass.

[73] Assignee: Itek Corporation, Lexington, Mass.

[22] Filed: Sept. 11, 1974 [21] Appl. No.: 504,470

[52] US. Cl 51/119; 51/58; 51/124 L; 51/156; 51/284 [51] Int. Cl. B241313/02 [58] Field of Search 51/58, 55, 156, 162, 284, 51/71, 119,120,124L, 57,54

[56] References Cited UNITED STATES PATENTS 766,482 8/1904 Wolfe 51/124L 998,101 7/1911 Laabs .51/105 LG 1,272,546 7/1918 Simpson 51/124 L1,292,926 l/l919 Troppman 51/124 L 2,975,565 3/1961 Phillips t. 51/124 L3,093,939 6/1963 Dalton.... 51/124 L 3,732,647 5/1973 Stith 51/119Primary Examiner-Donald G. Kelly Attorney, Agent, or Firml-lomer 0.Blair; Robert L. Nathans; Gerald H. Glanzman 1 1 ABSTRACT Apparatus forpolishing toroidal surfaces on ophthalmic lenses. In accordance with apreferred embodiment, a toroidal polishing tool is driven in anonrotating orbital manner while being supported by a gimbal havingpivot axes which are vertically displaced from one another so that thelapping surface of the tool will, in its movement, define and alwaysmove on a toroidal surface fixed in space. By properly spacing thegimbal axes relative to the vertex of the tool surface, the fixedtoroidal surface in space will have the same radial dimensions as thetool surface and the lens surface to be polished. Therefore, bypositioning the lens so that its surface will be on the fixed toroidalsurface in space, the lens will be effectively polished by the movingtoo] and can be held stationary throughout the polishing operation.Because the lens can be held stationary, greater machine speeds andpolishing rates can be achieved. An improved breakup motion is alsoprovided in the system to prevent the formation of ridges or grooves onthe lens surface.

14 Claims, 2 Drawing Figures MOTOR 29 l l l l PATENTED AUG 2 61975APPARATUS FOR POLISHING TOROIDAL SURFACES BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates generally to atoroidal polishing apparatus and, more particularly, to an apparatus forpolishing toroidal surfaces on ophthalmic lenses in a more rapid andefficient manner.

2. Description of the Prior Art A toroidal surface is a surface ofcompound curvature in which the circular curvature measured in thedirection of a first principal meridian of the surface is of a differentradial dimension than the circular curvature measured in the directionof a second principal meridian normal to and passing through the firstprincipal meridian. Such surfaces are important in many areas, but areparticularly useful in the ophthalmic field wherein lenses havingtoroidal surfaces are utilized for the correction of astigmatism.

Because of their importance in the ophthalmic field, a large variety ofdifferent systems have been developed to grind and polish such surfaces.The present invention is directed particularly to an apparatus forpolishing toroidal surfaces, although, it should be understood that theterm polishing as used herein is also intended to include fining whichis an intermediate step sometimes carried out between the grinding andpolishing steps.

In the typical toroidal polisher f the prior art, polishing is carriedout by moving a lens and a lapping tool, both of which have beenprovided with the desired toroidal surface, transversely relative to oneanother in a manner so as to effect polishing of the lens surface. Inconstructing a system so as to carry out this relative transversemovement, however, there are several design requirements which must besatisfied in order to produce good surfaces. For one thing, because atoroidal surface is not axially symmetrical, it is essential that thetool and the lens be prevented from rotating relative to one anotherduring the polishing operation. Instead, the corresponding principalmeridians of the lens and of the tool must be initially aligned andalways maintained parallel to one another. Because of this limitation,the practice has been to cause the lapping tool to move relative to thelens in a non-rotating orbital manner such that the meridians of thelens and the tool will remain aligned while still permitting the lensand the tool to move relative to one another to effect polishing.

Also, in order to prevent the formation of ridges or grooves on the lenssurface, it has been found necessary to introduce one or more break-up"motions into the relative movement between the lens and the tool so thatthe tool will not always move along the same path relative to the lens.These break-up motions may take a variety of forms as long as they donot change the polar alignment of the lens relative to the tool andfrequently comprise oscillations or reciprocations of one memberrelative to the other at different speeds or at different amplitudes.Because of these break-up mo tions several independent movements of boththe lens and the tool usually take place simultaneously during apolishing operation. This tends to make the system quite complex andsusceptible to becoming misaligned.

A third important limitation of the polishing system is that the lenssurface and the tool surface always be maintained fully in contact withone another without separating. Because of this requirement, and alsobecause the tool usually is moving in a variety of unrelated and usuallyirregular paths, it has been found necessary to mount the lens so thatit can follow the tool as it is carrying out these multiple motions.Usually this entails mounting the lens on some form of ball jointconnection so that the lens can wobble and adjust its position so as toalways remain in contact with the tool as the tool is carrying out itsseveral movements. Because of this need for the lens to wobble, theoverall polishing speed of the system must be reduced significantly.Specifically, in the typical system where the lens wobbles, the tool canusually be moved only at speeds of about 200300 r.p.m. and it frequentlytakes five minutes or more to polish a lens. This greatly slows down theentire lens manufacturing operation and makes it much less conductive toautomation.

SUMMARY OF THE PREFERRED EMBODIMENT By the present invention, the aboveinadequacies of the prior art have been significantly reduced byproviding a polishing system designed to permit the lens to be rigidlymounted in position and held stationary during the entire polishingoperation. In accordance with the presently most preferred embodiment,this capability is attained by designing the kinematics of the movabletool in such a manner that its toroidal lapping surface, by itsmovement, will define and always be positioned on a toroidal surfacefixed in space, which toroidal surface will have the same radialdimensions as the lapping surface and the toroidal surface to bepolished on the lens. By designing the system in this way, the lens canbe rigidly mounted to have its surface aligned on the fixed toroidalsurface in space, and, accordingly, as the lapping tool face moves alongthe surface, it will always be properly oriented and firmly in contactwith the lens surface so as to properly polish it.

The above-described tool movement is attained by coupling the tool to anorbital driving means through a gimbal coupling designed such that thetool will be free to pivot about two perpendicular axes which arevertically displaced from one another relative to the lens and lappingtool surfaces. Specifically, one axis of the gimbal is spaced from thevertex of the tool surface by a distance equal to the radius ofcurvature of the tool surface in the direction of one principal meridianwhile the second axis is spaced from the vertex by a distance equal tothe radius of curvature of the tool surface in the direction of thesecond principal meridian. Accordingly, as the tool is orbitally driven,its lapping face will automatically define and always move along theproper toroidal surface in space. In prior art systems, the tool iscoupled to a gimbal whose axes are in the same plane such that the toolface will not move along a toroidal surface in space, and it is for thisreason that the lens must be movably mounted to follow the tool.

The present invention also provides a novel breakup" motion for the toolto avoid the formation of ridges or grooves on the lens. Specifically,the tool is mounted such that the orbital motion applied to it willcontinuously change in amplitude between upper and lower limits. Thiscauses the tool to describe a spiral pattern relative to the lenssurface which will insure that different parts of the tool will becontacting different parts of the lens at all times. This one break-upmotion has been found sufficient to produce good quality lenses withoutadditional movements being necessary. Also, this motion has beendesigned such that the tool surface will still define and remain on theproper toroidal surface in space at all times.

Bacause of the above described kinematics, the lens can be maintainedstationary throughout the polishing operation. This permits much higherpolishing speeds and improved surface quality to be obtained. Forexample, tool speeds of 2,000 c.p.m. and polishing rates of 1-2 minutesper lens are obtainable.

Also, because the lens can be mounted rigidly rela tive to the tool, thepresent polishing system is particularly well adapted for automation.For example, the lens can be mounted on a conveyor system that willsequentially feed the lenses into position for polishing one at a time.This cannot readily be done in prior art systems where the lens must beable to wobble relative to the tool. Further features of the inventionwill be discussed hereinafter in conjunction with the detaileddescription of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates atoroidal polishing system in accordance with a presently preferredembodiment of the invention.

FIG. 2 graphically illustrates the kinematics of the lapping tool in thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematicallyillustrates an apparatus for polishing toroidal surfaces in accordancewith a presently preferred embodiment of the invention. In the FIG.,reference number refers generally to a lens having a surface 11 toaround a be polished. Lens surface 11 has been previously provided withthe desired toroidal surface by any conventional procedure and isillustrated more clearly in dotted line in FIG. 2. Specifically, lenssurface 11 has been generated to have a curvature of radius R in thedirection of a first principal meridian BB, and a curvature of radius Rin the direction of a second principal meridian CC perpendicular to thefirst principal meridian.

Referring back to FIG. 1, lens 10 is held on suitable support 12 bymeans of a lens block 13 to which the lens has been adhered so that whenblock 13 is inserted in support 12, lens surface 11 will be properlyoriented within the polishing system as is understood by those skilledin the art.

Polishing of lens surface 11 is accomplished by a lapping tool 14 whichmay be of conventional type and which has been provided with a lappingsurface 16 having the same toroidal shape as the lens surface ll.Although it is not illustrated in the drawings for purposes of clarity,means are also provided in the system to deposit an appropriatepolishing mixture over the lens surface 11 so that as the tool 14 ismoved thereover, the appropriate polishing action can take place.

As mentioned above, since toroidal surfaces are not axially symmetrical,it is essential that the tool and lens surfaces be initially alignedwith respect to one another and maintained in alignment throughout theentire polishing operation. In other words, it is essential that theprincipal meridians 8-8 and CC of lens surfaces 11 be maintainedparallel with the corresponding principal meridians of lapping toolsurface 16 at all times. Initial alignment is obtained automatically bythe proper mounting of the lens block 13 as mentioned above. Thereafter,to maintain alignment, any movement of the tool relative to the lensmust be without rotation, and, to achieve this, it has become thepractice in the art to drive the tool in a non-rotating orbital mannerover the lens. This technique is also utilized in the present invention,and appropriate structure for establishing this type of motion isschematically illustrated in FIG. 1 and identified by reference number17. Specifically, orbital driving means 17 is coupled to tool 14 by ashaft 20 such that as it is driven in an orbital path of radius R, by amotor 18 as indicated by arrow 19, the tool will also move in anonrotating orbital manner relative to the lens 10. The specificstructure of the orbital driving means has not been illustrated forpurposes of clarity and because it may take many forms that are known inthe art. Examples of such systems, however, are illustrated in US. Pat.Nos. 998,101 to Laabs and 3,732,647 to Stith. Orbital driving means 17is also positioned so that it, and hence the tool, will orbit aroundvertex axis 25 which extends through the vertex V,, of lens surface 11.

Supporting tool 14 for orbital movement over the lens surface is agimbal mount illustrated generally by reference number 40, which mountforms an important aspect of the present invention. Specifically, in thetypical toroidal polisher, the tool is supported by a gimbal havingperpendicular axes positioned in the same plane. Accordingly, as thetool is moved orbitally over the lens, its pivotal movement around thegimbal will cause it to describe a spherical surface in space. Because,however, the lens surface is not spherical, but instead is toroidal, toensure that the lens surface is always in proper contact with the toolsurface, it is necessary to mount the lens so that it can wobble andtilt to follow the too]. As mentioned above, this necessitates areduction in polishing speeds and creates other problems. In the presentinvention, however, the gimbal has been designed to overcome theseinadequacies. In particular, the gimbal 40 is designed to have pivotaxes 21 and 22 which are vertically displaced from one another relativeto tool surface 16. Furthermore, axis 21 is spaced from the vertex V ofthe tool surface by a distance of R which corresponds to the radius ofthe curvature of the tool and lens surfaces in the direction of majormeridian BB, while axis 22 is spaced from vertex V, by a distance of Rwhich corresponds to the radius of the curvature of the tool and lenssurfaces in the direction of major meridian CC.

By separating and precisely positioning the pivot axes of the gimbal inthis manner, the improved kinematics of the present invention areeffectively attained. Specifically, as the tool is being carried aroundthe lens in an orbital manner by orbital driving means 17, it will befree to pivot in and out of the plane of FIG. 1 aroudn axis 21 such thatsurface 16 will describe around curved path of radius R in thatdirection. Simulta neously, it will be free to pivot back and forth inthe plane of FIG. 1 around axis 22 so as to describe a curved path ofradius R in that direction. Therefore, it should be apparent that whenthe tool is driven in one complete orbit around axis 25, its surface 16will define a toroidal surface 31 in space (FIG. 2), which toroidalsurface will have the same radii of curvature R and R in the directionof its major meridians B-B' and C 'C', respectively, as lens surface 11and tool surface Furthermore, since axes 21 and 22 are fixed in space,the toroidal surface 31 will also be fixed in space and the tool surface16 will always be positioned on and occupy a portion of it. Accordingly,by positioning lens so that its surface 11 will be aligned and coincidewith that toroidal surface in space (i.e. with meridians 8-8 and CCcoinciding with meridians B-B' and C-C'), the lens surface 11 willalways be in proper contact with the tool and will be polished by it.Since the fixed toroidal surface in space will be fixed, the lens canalso be maintained stationary at all times.

This concept can be better understood with reference to FIG. 2 whichgraphically depicts the kinematics of the system. Specifically, when thetool (not shown in FIG. 2) makes a single orbit around the lens 10 whilebeing free to pivot around axes 21 and 22 as indicated by arrows 32 and33, respectively, its surface 16 will define toroidal surface 31 inspace. Because axis 21 is spaced from the vertex V, of the lens surface11 by a distance R and because axis 22 is spaced therefrom by a distanceof R this generated surface in space will have the same radii ofcurvature as lens surface 11 and tool surface 16. Furthermore, becausethe lens has been properly oriented in the system, the generated surface31 will have its major axes B'B' and C'C' parallel to and coincidingwith axes 8-8 and CC of lens surface 1 1. Therefore, if the lens surface11, shown in dotted line in FIG. 2, is held stationary on surface 31, asthe tools move on that surface it will automatically be on the lenssurface at all times and will properly polish it.

Referring back now to FIG. 1, it was mentioned above, that suitablebreak-up motions must be superimposed over the basic orbital movement ofthe tool so as to vary the path of the tool relative to the lens so asto prevent the formation of any ridges or grooves on the lens as mightbe caused by any imperfections in the tool surface. This is alsonecessary in the present system and appropriate structure is illustratedschematically by reference number 23. Specifically, the orbital drivingmeans 17 is coupled by means of a linkage 24 to a plunger 26. Plunger 26is, in turn, adapted to be moved up and down within a sleeve 27 asindicated by arrow 28 under control of a suitable motor 29 which mayconveniently be a simple pneumatic system. From FIG. 1, it should beapparent that as plunger 26 is moved back and forth within sleeve 27,the radius R of the orbital driving means 17 will vary. In particular,the radius R of the orbit will vary between a first maximum radialdimension and a second minimum radial dimension in a continuous manner.This, in turn, will cause the face of the tool to move in an orbit ofcontinuously varying amplitude and the effect will be that every pointon the tool face will move in a spiral path relative to the lenssurface. Because of this, every point of the tool face will move over adifferent part of the lens during every orbital cycle, and this willavoid the formation of grooves or ridges. Inasmuch as this break-upmotion does nothing more than vary the amplitude of the orbit, it willnot affect the shape of toroidal surface 31 in space. The face 16 of thetool will still always be on that surface and hence, will always beproperly mated with the lens surface and, therefore, the lens can stillbe maintained stationary.

It has also been found that this single break-up mo tion is adequate toproduce good quality surfaces with out any further break-up movementsbeing necessary This results in a substantial simplification of the kinematics over prior art systems where several indepen dent break-upmotions are frequently necessary.

In an operative embodiment of the present invention the tool can beorbited at speeds of about 1,000 l.( about 2,000 c.p.m. while plunger 26is moved up am down at about 20 cycles per minute to vary the radiu: Rbetween about 0.1 to about 1.0 inches. These oper ating parameterspermit a typical lens to be polished it about 1 to 2 minutes.

In summary, the present invention provides a polish ing system capableof polishing lenses more rapidly ant effectively than heretofore. Thisis made possible be cause the lens can be maintained stationary at alltime: during the polishing operation. Also, because fewer break-upmovements are needed, a somewhat less com plex system is made possible.To polish toroidal lense: of differing curvature, it is only necessaryto change tt the appropriate tool, and adjust the gimbal axes 21 311C 22to be spaced from the lens by new distances corresponding to the radiiof curvature of the new lens to be polished. Also, with the presentinvention, it becomes a relatively simple matter to automate thepolishing operation. Specifically, as is illustrated in FIG. 1, becausethe lenses can be supported rigidly, a production line system can be setup by which lenses are fed one at 2 time into position to be polished.After lens 10 has beer. polished, for example, movable support 12 can beactuated and moved in the direction indicated by arrow 41 to feed thenext lens 10 into position to polish its surface 11'. Where the lensesmust be mounted on a movable support, automation would be much moredifficull to achieve.

While what has been described is a presently most preferred embodiment,it should be understood that various additions, changes, and omissionsmay be made from the invention. For example, it is possible, withoutdeparting from the invention, to maintain the tool stationary and movethe lens relative to it. Also, the system would find use in polishingworkpieces other than lenses. Accordingly, the invention should belimited only insofar as required by the scope of the following claims.

I claim:

1. Apparatus for polishing toroidal surfaces comprisa. a first memberand a second member, one of said members comprising a lapping toolhaving a toroidal lapping surface and the other of said memberscomprising means for carrying a workpiece having a toroidal workpiecesurface to be polished, the toroidal surfaces of both said lapping tooland said workpiece having a curvature of a first radius in the directionof a first principal meridian thereof and a curvature of a second radiusdifferent from said first radius in the direction of a second principalmeridian thereof perpendicular to said first principal meridian;

b. means for supporting said first member for pivotal movement in firstand second curved paths, said first curved path being parallel to saidfirst principal meridian of the toroidal surface thereof and having aradius equal to said first radius, and said second curved path beingparallel to said second principal meridian of the toroidal surfacethereof and having a radius equal to said second radius;

0. drive means for driving said first member in a nonrotating orbitalmanner, said support means causing the toroidal surface of said firstmember to define and always move in a fixed toroidal surface in space,said fixed toroidal surface in space having the same radial dimensionsas the toroidal surfaces of said first and second members; and

d. means for positioning the toroidal surface of said second member onsaid fixed toroidal surface in space such that during the movement ofsaid first member thereon said workpiece surface will be polished bysaid lapping tool.

2. Apparatus as recited in claim 1 wherein said support means comprisesgimbal means having first and second axes which are perpendicular toeach other and perpendicular to said first and second principalmeridians, respectively, and wherein said first and second axes arespaced from the vertex of the toroidal surface of said first member bydistances equal to said first and second radii, respectively.

3. Apparatus as recited in claim 2, and further including means formaintaining said second member substantially stationary relative to saidfirst member with the first and second principal meridians of thetoroidal surface thereof parallel to the first and second principalmeridians of said fixed toroidal surface in space.

4. Apparatus as recited in claim 3, wherein said first member comprisessaid lapping tool, and wherein said second member comprises said meansfor carrying said workpiece.

5. Apparatus as recited in claim 3 and further including means forintroducing a breakup motion into the movement of said first member tovary the path of movement of said first member relative to said secondmember.

6. Apparatus as recited in claim 5 wherein said breakup motionintroducing means comprises means for continuously varying the amplitudeof the orbit of said first member.

7. The apparatus as recited in claim 6 wherein said drive means drivessaid first member at an orbital speed of between about 1,000 and 2,000c.p.m.

8. Apparatus as recited in claim 6 wherein said first member comprisessaid lapping tool and wherein said second member comprises said meansfor carrying said workpiece.

9. Apparatus as recited in claim 8 wherein said workpiece comprises alens.

10. Apparatus as recited in claim 9 wherein said means for carrying saidlens comprises conveyor means carrying a plurality of lenses to bepolished, said conveyor means including means for positioning saidplurality of lenses, one at a time, on said fixed toroidal surface inspace to be polished by saidlapping tool.

11. Apparatus for polishing toroidal surfaces comprising:

a. a lapping tool having a toroidal lapping surface,

said toroidal lapping surface having a curvature of a first radius inthe direction of a first principal meridian thereof and a curvature of asecond radius different from said first radius in the direction of asecond principal meridian perpendicular to said first principalmeridian;

b. means for supporting said lapping tool for pivotal movement in firstand second curved paths, said first and second paths being parallel tosaid first and second principal meridians, respectively, and havingradii equal to said first and second radii, respectively;

c. drive means for driving said lapping tool in a nonrotating orbitalmanner whereby said support means will cause the toroidal surface ofsaid lapping tool to define and always move on a fixed toroidal surfacein space, said fixed toroidal surface in space having the same radialdimensions as said toroidal lapping surface; and

d. means for positioning a workpiece having a toroidal surface to bepolished on said fixed toroidal surface in space such that the movementof said lapping tool thereon will effect polishing of said workpiece.

12. Apparatus as recited in claim 11 wherein said workpiece positioningmeans comprises means for maintaining the surface thereof stationary onsaid toroidal surface fixed in space.

13. Apparatus as recited in claim 12 wherein said support meanscomprises gimbal means having first and second axes which areperpendicular to each other and perpendicular to said first and secondprincipal meridians, respectively, and wherein said first and secondaxes are spaced from the vertex of the toroidal lapping surface bydistances equal to said first and second radii, respectively.

14. Apparatus as recited in claim 13 and further including means forintroducing a breakup motion into the movement of said lapping tool tovary the path of movement of said lapping tool relative to saidworkpiece.

1. Apparatus for polishing toroidal surfaces comprising: a. a firstmember and a second member, one of said members comprising a lappingtool having a toroidal lapping surface and the other of said memberscomprising means for carrying a workpiece having a toroidal workpiecesurface to be polished, the toroidal surfaces of both said lapping tooland said workpiece having a curvature of a first radius in the directionof a first principal meridian thereof and a curvature of a second radiusdifferent from said first radius in the direction of a second principalmeridian thereof perpendicular to said first principal meridian; b.means for supporting said first member for pivotal movement in first andsecond curved paths, said first curved path being parallel to said firstprincipal meridian of the toroidal surface thereof and having a radiusequal to said first radius, and said second curved path being parallelto said second principal meridian of the toroidal surface thereof andhaving a radius equal to said second radius; c. drive means for drivingsaid first member in a non-rotating orbital manner, said support meanscausing the toroidal surface of said first member to define and alwaysmove in a fixed toroidal surface in space, said fixed toroidal surfacein space having the same radial dimensions as the toroidal surfaces ofsaid first and second members; and d. means for positioning the toroidalsurface of said second member on said fixed toroidal surface in spacesuch that during the movement of said first member thereon saidworkpiece surface will be polished by said lapping tool.
 2. Apparatus asrecited in claim 1 wherein said support means comprises gimbal meanshaving first and second axes which are perpendicular to each other andperpendicular to said first and second principal meridians,respectively, and wherein said first and second axes are spaced from thevertex of the toroidal surface of said first member by distances equalto said first and second radii, respectively.
 3. Apparatus as recited inclaim 2, and further including means for maintaining said second membersubstantially stationary relative to said first member with the firstand second principal meridians of the toroidal surface thereof parallelto the first and second principal meridians of said fixed toroidalsurface in space.
 4. Apparatus as recited in claim 3, wherein said firstmember comprises said lapping tool, and wherein said second membercomprises said means for carrying said workpiece.
 5. Apparatus asrecited in claim 3 and further including means for introducing a breakupmotion into the movement of said first member to vary the path ofmovement of said first member relative to said second member. 6.Apparatus as recited in claim 5 wherein said breakup motion introducingmeans comprises means for continuously varying the amplitude of theorbit of said first member.
 7. The apparatus as recited in claim 6wherein said drive means drives said first member at an orbital speed ofbetween about 1, 000 and 2,000 c.p.m.
 8. Apparatus as recited in claim 6wherein said first member comprises said lapping tool and wherein saidsecond member comprises said means for carrying said workpiece. 9.Apparatus as recited in claim 8 wherein said workpiece comprises a lens.10. Apparatus as recited in claim 9 wherein said means for carrying saidlens comprises conveyor means carrying a plurality of lenses to bepolished, said conveyor means including means for positioning saidplurality of lenses, one at a time, on said fixed toroidal surface inspace to be polished by said lapping tool.
 11. Apparatus for polishingtoroidal surfaces comprising: a. a lapping tool having a toroidallapping surface, said toroidal lapping surface having a curvature of afirst radius in the direction of a first principal meridian thereof anda curvature of a second radius different from said first radius in thedirection of a second principal meridian perpendicular to said firstprincipal meridian; b. means for supporting said lapping tool forpivotal movement in first and second curved paths, said first and secondpaths being parallel to said first and second principal meridians,respectively, and having radii equal to said first and second radii,respectively; c. drive means for driving said lapping tool in anon-rotating orbital manner whereby said support means will cause thetoroidal surface of said lapping tool to define and always move on afixed toroidal surface in space, said fixed toroidal surface in spacehaving the same radial dimensions as said toroidal lapping surface; andd. means for positioning a workpiece having a toroidal surface to bepolished on said fixed toroidal surface in space such that the movementof said lapping tool thereon will effect polishing of said workpiece.12. Apparatus as recited in claim 11 wherein said workpiece positioningmeans comprises means for maintaining the surface thereof stationary onsaid toroidal surface fixed in space.
 13. Apparatus as recited in claim12 wherein said support means comprises gimbal means having first andsecond axes which are perpendicular to each other and perpendicular tosaid first and second principal meridians, respectively, and whereinsaid first and second axes are spaced from the vertex of the toroidallapping surface by distances equal to said first and second radii,respectively.
 14. Apparatus as recited in claim 13 and further includingmeans for introducing a breakup motion into the movement of said lappingtool to vary the path of movement of said lapping tool relative to saidworkpiece.